Molecular Characterization of Quinate and Shikimate Metabolism in Populus trichocarpa

Abstract

Background: Shikimate is essential for protein biosynthesis. Quinate and its derivatives are protective secondary metabolites. Results: Members of the same gene family encode enzymes with either shikimate or quinate dehydrogenase activity. Conclusion:The molecular genetic basis of plant quinate metabolism has been unraveled in vitro. Significance: Identifying quinate metabolic enzymes will allow testing its ecological function and may enable biotechnological applications.

Evolution of a secondary metabolic pathway from primary metabolism: shikimate and quinate biosynthesis in plants

“…While PoptrQDH2 showed higher specificity towards quinate than shikimate (Guo et al ., ), PintaQDH showed roughly equal specificity towards both compounds. This is consistent with work by Ossipov et al .…”

“…Like all SDHs tested here, PintaQDH is dependent on NADP + as a cofactor and showed negligible activities close to the detection limit (not exceeding 0.4 μmol mg −1 min −1 ) when NAD + was used as a cofactor instead for both SDH and QDH activities. Showing the opposite trend, poplar QDHs preferred NAD + to NADP + as a cofactor with either shikimate or quinate as a substrate, as previously described (Guo et al ., ).…”

“…None of the gymnosperm sequences forming the sister clade to the angiosperm SDHs have been characterized previously, but because of its phylogenetic position we denoted this clade as the gymnosperm SDH clade. In contrast, the previously characterized QDHs from P. trichocarpa ( PoptrQDH1 and PoptrQDH2 ) (Guo et al ., ) are the only biochemically characterized members of the second clade (Figure ), which we refer to as the angiosperm QDH clade. None of the gymnosperm sister clade members have been previously characterized, but again solely because of its phylogenetic position we denoted this clade as QDH.…”

“…Anc122 represents the pre‐duplication ancestor sequence reconstructed from the phylogeny. SDH1 and QDH2 from Populus trichocarpa (Poptr) (Guo et al ., ) were included as controls for comparison.…”

“…It is worth noting that in both the SDH and QDH clades additional (more recent) gene duplications and losses took place, shaping complex gene families in some seed plants clades. Within each clade, P. trichocarpa duplicates do not seem to be biochemically distinct, but show differential expression patterns during development and in response to environmental cues (Guo et al ., ) suggesting physiological divergence. Gritsunov et al .…”